git.oblomov.eu Git - linux-2.6/blob - fs/ocfs2/stackglue.c

   1 /* -*- mode: c; c-basic-offset: 8; -*-
   2  * vim: noexpandtab sw=8 ts=8 sts=0:
   3  *
   4  * stackglue.c
   5  *
   6  * Code which implements an OCFS2 specific interface to underlying
   7  * cluster stacks.
   8  *
   9  * Copyright (C) 2007, 2009 Oracle.  All rights reserved.
  10  *
  11  * This program is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU General Public
  13  * License as published by the Free Software Foundation, version 2.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18  * General Public License for more details.
  19  */
  20
  21 #include <linux/list.h>
  22 #include <linux/spinlock.h>
  23 #include <linux/module.h>
  24 #include <linux/slab.h>
  25 #include <linux/kmod.h>
  26 #include <linux/fs.h>
  27 #include <linux/kobject.h>
  28 #include <linux/sysfs.h>
  29 #include <linux/sysctl.h>
  30
  31 #include "ocfs2_fs.h"
  32
  33 #include "stackglue.h"
  34
  35 #define OCFS2_STACK_PLUGIN_O2CB         "o2cb"
  36 #define OCFS2_STACK_PLUGIN_USER         "user"
  37 #define OCFS2_MAX_HB_CTL_PATH           256
  38
  39 static struct ocfs2_locking_protocol *lproto;
  40 static DEFINE_SPINLOCK(ocfs2_stack_lock);
  41 static LIST_HEAD(ocfs2_stack_list);
  42 static char cluster_stack_name[OCFS2_STACK_LABEL_LEN + 1];
  43 static char ocfs2_hb_ctl_path[OCFS2_MAX_HB_CTL_PATH] = "/sbin/ocfs2_hb_ctl";
  44
  45 /*
  46  * The stack currently in use.  If not null, active_stack->sp_count > 0,
  47  * the module is pinned, and the locking protocol cannot be changed.
  48  */
  49 static struct ocfs2_stack_plugin *active_stack;
  50
  51 static struct ocfs2_stack_plugin *ocfs2_stack_lookup(const char *name)
  52 {
  53         struct ocfs2_stack_plugin *p;
  54
  55         assert_spin_locked(&ocfs2_stack_lock);
  56
  57         list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
  58                 if (!strcmp(p->sp_name, name))
  59                         return p;
  60         }
  61
  62         return NULL;
  63 }
  64
  65 static int ocfs2_stack_driver_request(const char *stack_name,
  66                                       const char *plugin_name)
  67 {
  68         int rc;
  69         struct ocfs2_stack_plugin *p;
  70
  71         spin_lock(&ocfs2_stack_lock);
  72
  73         /*
  74          * If the stack passed by the filesystem isn't the selected one,
  75          * we can't continue.
  76          */
  77         if (strcmp(stack_name, cluster_stack_name)) {
  78                 rc = -EBUSY;
  79                 goto out;
  80         }
  81
  82         if (active_stack) {
  83                 /*
  84                  * If the active stack isn't the one we want, it cannot
  85                  * be selected right now.
  86                  */
  87                 if (!strcmp(active_stack->sp_name, plugin_name))
  88                         rc = 0;
  89                 else
  90                         rc = -EBUSY;
  91                 goto out;
  92         }
  93
  94         p = ocfs2_stack_lookup(plugin_name);
  95         if (!p || !try_module_get(p->sp_owner)) {
  96                 rc = -ENOENT;
  97                 goto out;
  98         }
  99
 100         active_stack = p;
 101         rc = 0;
 102
 103 out:
 104         /* If we found it, pin it */
 105         if (!rc)
 106                 active_stack->sp_count++;
 107
 108         spin_unlock(&ocfs2_stack_lock);
 109         return rc;
 110 }
 111
 112 /*
 113  * This function looks up the appropriate stack and makes it active.  If
 114  * there is no stack, it tries to load it.  It will fail if the stack still
 115  * cannot be found.  It will also fail if a different stack is in use.
 116  */
 117 static int ocfs2_stack_driver_get(const char *stack_name)
 118 {
 119         int rc;
 120         char *plugin_name = OCFS2_STACK_PLUGIN_O2CB;
 121
 122         /*
 123          * Classic stack does not pass in a stack name.  This is
 124          * compatible with older tools as well.
 125          */
 126         if (!stack_name || !*stack_name)
 127                 stack_name = OCFS2_STACK_PLUGIN_O2CB;
 128
 129         if (strlen(stack_name) != OCFS2_STACK_LABEL_LEN) {
 130                 printk(KERN_ERR
 131                        "ocfs2 passed an invalid cluster stack label: \"%s\"\n",
 132                        stack_name);
 133                 return -EINVAL;
 134         }
 135
 136         /* Anything that isn't the classic stack is a user stack */
 137         if (strcmp(stack_name, OCFS2_STACK_PLUGIN_O2CB))
 138                 plugin_name = OCFS2_STACK_PLUGIN_USER;
 139
 140         rc = ocfs2_stack_driver_request(stack_name, plugin_name);
 141         if (rc == -ENOENT) {
 142                 request_module("ocfs2_stack_%s", plugin_name);
 143                 rc = ocfs2_stack_driver_request(stack_name, plugin_name);
 144         }
 145
 146         if (rc == -ENOENT) {
 147                 printk(KERN_ERR
 148                        "ocfs2: Cluster stack driver \"%s\" cannot be found\n",
 149                        plugin_name);
 150         } else if (rc == -EBUSY) {
 151                 printk(KERN_ERR
 152                        "ocfs2: A different cluster stack is in use\n");
 153         }
 154
 155         return rc;
 156 }
 157
 158 static void ocfs2_stack_driver_put(void)
 159 {
 160         spin_lock(&ocfs2_stack_lock);
 161         BUG_ON(active_stack == NULL);
 162         BUG_ON(active_stack->sp_count == 0);
 163
 164         active_stack->sp_count--;
 165         if (!active_stack->sp_count) {
 166                 module_put(active_stack->sp_owner);
 167                 active_stack = NULL;
 168         }
 169         spin_unlock(&ocfs2_stack_lock);
 170 }
 171
 172 int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin)
 173 {
 174         int rc;
 175
 176         spin_lock(&ocfs2_stack_lock);
 177         if (!ocfs2_stack_lookup(plugin->sp_name)) {
 178                 plugin->sp_count = 0;
 179                 plugin->sp_proto = lproto;
 180                 list_add(&plugin->sp_list, &ocfs2_stack_list);
 181                 printk(KERN_INFO "ocfs2: Registered cluster interface %s\n",
 182                        plugin->sp_name);
 183                 rc = 0;
 184         } else {
 185                 printk(KERN_ERR "ocfs2: Stack \"%s\" already registered\n",
 186                        plugin->sp_name);
 187                 rc = -EEXIST;
 188         }
 189         spin_unlock(&ocfs2_stack_lock);
 190
 191         return rc;
 192 }
 193 EXPORT_SYMBOL_GPL(ocfs2_stack_glue_register);
 194
 195 void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin)
 196 {
 197         struct ocfs2_stack_plugin *p;
 198
 199         spin_lock(&ocfs2_stack_lock);
 200         p = ocfs2_stack_lookup(plugin->sp_name);
 201         if (p) {
 202                 BUG_ON(p != plugin);
 203                 BUG_ON(plugin == active_stack);
 204                 BUG_ON(plugin->sp_count != 0);
 205                 list_del_init(&plugin->sp_list);
 206                 printk(KERN_INFO "ocfs2: Unregistered cluster interface %s\n",
 207                        plugin->sp_name);
 208         } else {
 209                 printk(KERN_ERR "Stack \"%s\" is not registered\n",
 210                        plugin->sp_name);
 211         }
 212         spin_unlock(&ocfs2_stack_lock);
 213 }
 214 EXPORT_SYMBOL_GPL(ocfs2_stack_glue_unregister);
 215
 216 void ocfs2_stack_glue_set_locking_protocol(struct ocfs2_locking_protocol *proto)
 217 {
 218         struct ocfs2_stack_plugin *p;
 219
 220         BUG_ON(proto == NULL);
 221
 222         spin_lock(&ocfs2_stack_lock);
 223         BUG_ON(active_stack != NULL);
 224
 225         lproto = proto;
 226         list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
 227                 p->sp_proto = lproto;
 228         }
 229
 230         spin_unlock(&ocfs2_stack_lock);
 231 }
 232 EXPORT_SYMBOL_GPL(ocfs2_stack_glue_set_locking_protocol);
 233
 234
 235 /*
 236  * The ocfs2_dlm_lock() and ocfs2_dlm_unlock() functions take
 237  * "struct ocfs2_lock_res *astarg" instead of "void *astarg" because the
 238  * underlying stack plugins need to pilfer the lksb off of the lock_res.
 239  * If some other structure needs to be passed as an astarg, the plugins
 240  * will need to be given a different avenue to the lksb.
 241  */
 242 int ocfs2_dlm_lock(struct ocfs2_cluster_connection *conn,
 243                    int mode,
 244                    union ocfs2_dlm_lksb *lksb,
 245                    u32 flags,
 246                    void *name,
 247                    unsigned int namelen,
 248                    struct ocfs2_lock_res *astarg)
 249 {
 250         BUG_ON(lproto == NULL);
 251
 252         return active_stack->sp_ops->dlm_lock(conn, mode, lksb, flags,
 253                                               name, namelen, astarg);
 254 }
 255 EXPORT_SYMBOL_GPL(ocfs2_dlm_lock);
 256
 257 int ocfs2_dlm_unlock(struct ocfs2_cluster_connection *conn,
 258                      union ocfs2_dlm_lksb *lksb,
 259                      u32 flags,
 260                      struct ocfs2_lock_res *astarg)
 261 {
 262         BUG_ON(lproto == NULL);
 263
 264         return active_stack->sp_ops->dlm_unlock(conn, lksb, flags, astarg);
 265 }
 266 EXPORT_SYMBOL_GPL(ocfs2_dlm_unlock);
 267
 268 int ocfs2_dlm_lock_status(union ocfs2_dlm_lksb *lksb)
 269 {
 270         return active_stack->sp_ops->lock_status(lksb);
 271 }
 272 EXPORT_SYMBOL_GPL(ocfs2_dlm_lock_status);
 273
 274 int ocfs2_dlm_lvb_valid(union ocfs2_dlm_lksb *lksb)
 275 {
 276         return active_stack->sp_ops->lvb_valid(lksb);
 277 }
 278 EXPORT_SYMBOL_GPL(ocfs2_dlm_lvb_valid);
 279
 280 void *ocfs2_dlm_lvb(union ocfs2_dlm_lksb *lksb)
 281 {
 282         return active_stack->sp_ops->lock_lvb(lksb);
 283 }
 284 EXPORT_SYMBOL_GPL(ocfs2_dlm_lvb);
 285
 286 void ocfs2_dlm_dump_lksb(union ocfs2_dlm_lksb *lksb)
 287 {
 288         active_stack->sp_ops->dump_lksb(lksb);
 289 }
 290 EXPORT_SYMBOL_GPL(ocfs2_dlm_dump_lksb);
 291
 292 int ocfs2_stack_supports_plocks(void)
 293 {
 294         return active_stack && active_stack->sp_ops->plock;
 295 }
 296 EXPORT_SYMBOL_GPL(ocfs2_stack_supports_plocks);
 297
 298 /*
 299  * ocfs2_plock() can only be safely called if
 300  * ocfs2_stack_supports_plocks() returned true
 301  */
 302 int ocfs2_plock(struct ocfs2_cluster_connection *conn, u64 ino,
 303                 struct file *file, int cmd, struct file_lock *fl)
 304 {
 305         WARN_ON_ONCE(active_stack->sp_ops->plock == NULL);
 306         if (active_stack->sp_ops->plock)
 307                 return active_stack->sp_ops->plock(conn, ino, file, cmd, fl);
 308         return -EOPNOTSUPP;
 309 }
 310 EXPORT_SYMBOL_GPL(ocfs2_plock);
 311
 312 int ocfs2_cluster_connect(const char *stack_name,
 313                           const char *group,
 314                           int grouplen,
 315                           void (*recovery_handler)(int node_num,
 316                                                    void *recovery_data),
 317                           void *recovery_data,
 318                           struct ocfs2_cluster_connection **conn)
 319 {
 320         int rc = 0;
 321         struct ocfs2_cluster_connection *new_conn;
 322
 323         BUG_ON(group == NULL);
 324         BUG_ON(conn == NULL);
 325         BUG_ON(recovery_handler == NULL);
 326
 327         if (grouplen > GROUP_NAME_MAX) {
 328                 rc = -EINVAL;
 329                 goto out;
 330         }
 331
 332         new_conn = kzalloc(sizeof(struct ocfs2_cluster_connection),
 333                            GFP_KERNEL);
 334         if (!new_conn) {
 335                 rc = -ENOMEM;
 336                 goto out;
 337         }
 338
 339         memcpy(new_conn->cc_name, group, grouplen);
 340         new_conn->cc_namelen = grouplen;
 341         new_conn->cc_recovery_handler = recovery_handler;
 342         new_conn->cc_recovery_data = recovery_data;
 343
 344         /* Start the new connection at our maximum compatibility level */
 345         new_conn->cc_version = lproto->lp_max_version;
 346
 347         /* This will pin the stack driver if successful */
 348         rc = ocfs2_stack_driver_get(stack_name);
 349         if (rc)
 350                 goto out_free;
 351
 352         rc = active_stack->sp_ops->connect(new_conn);
 353         if (rc) {
 354                 ocfs2_stack_driver_put();
 355                 goto out_free;
 356         }
 357
 358         *conn = new_conn;
 359
 360 out_free:
 361         if (rc)
 362                 kfree(new_conn);
 363
 364 out:
 365         return rc;
 366 }
 367 EXPORT_SYMBOL_GPL(ocfs2_cluster_connect);
 368
 369 /* If hangup_pending is 0, the stack driver will be dropped */
 370 int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
 371                              int hangup_pending)
 372 {
 373         int ret;
 374
 375         BUG_ON(conn == NULL);
 376
 377         ret = active_stack->sp_ops->disconnect(conn);
 378
 379         /* XXX Should we free it anyway? */
 380         if (!ret) {
 381                 kfree(conn);
 382                 if (!hangup_pending)
 383                         ocfs2_stack_driver_put();
 384         }
 385
 386         return ret;
 387 }
 388 EXPORT_SYMBOL_GPL(ocfs2_cluster_disconnect);
 389
 390 /*
 391  * Leave the group for this filesystem.  This is executed by a userspace
 392  * program (stored in ocfs2_hb_ctl_path).
 393  */
 394 static void ocfs2_leave_group(const char *group)
 395 {
 396         int ret;
 397         char *argv[5], *envp[3];
 398
 399         argv[0] = ocfs2_hb_ctl_path;
 400         argv[1] = "-K";
 401         argv[2] = "-u";
 402         argv[3] = (char *)group;
 403         argv[4] = NULL;
 404
 405         /* minimal command environment taken from cpu_run_sbin_hotplug */
 406         envp[0] = "HOME=/";
 407         envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
 408         envp[2] = NULL;
 409
 410         ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);
 411         if (ret < 0) {
 412                 printk(KERN_ERR
 413                        "ocfs2: Error %d running user helper "
 414                        "\"%s %s %s %s\"\n",
 415                        ret, argv[0], argv[1], argv[2], argv[3]);
 416         }
 417 }
 418
 419 /*
 420  * Hangup is a required post-umount.  ocfs2-tools software expects the
 421  * filesystem to call "ocfs2_hb_ctl" during unmount.  This happens
 422  * regardless of whether the DLM got started, so we can't do it
 423  * in ocfs2_cluster_disconnect().  The ocfs2_leave_group() function does
 424  * the actual work.
 425  */
 426 void ocfs2_cluster_hangup(const char *group, int grouplen)
 427 {
 428         BUG_ON(group == NULL);
 429         BUG_ON(group[grouplen] != '\0');
 430
 431         ocfs2_leave_group(group);
 432
 433         /* cluster_disconnect() was called with hangup_pending==1 */
 434         ocfs2_stack_driver_put();
 435 }
 436 EXPORT_SYMBOL_GPL(ocfs2_cluster_hangup);
 437
 438 int ocfs2_cluster_this_node(unsigned int *node)
 439 {
 440         return active_stack->sp_ops->this_node(node);
 441 }
 442 EXPORT_SYMBOL_GPL(ocfs2_cluster_this_node);
 443
 444
 445 /*
 446  * Sysfs bits
 447  */
 448
 449 static ssize_t ocfs2_max_locking_protocol_show(struct kobject *kobj,
 450                                                struct kobj_attribute *attr,
 451                                                char *buf)
 452 {
 453         ssize_t ret = 0;
 454
 455         spin_lock(&ocfs2_stack_lock);
 456         if (lproto)
 457                 ret = snprintf(buf, PAGE_SIZE, "%u.%u\n",
 458                                lproto->lp_max_version.pv_major,
 459                                lproto->lp_max_version.pv_minor);
 460         spin_unlock(&ocfs2_stack_lock);
 461
 462         return ret;
 463 }
 464
 465 static struct kobj_attribute ocfs2_attr_max_locking_protocol =
 466         __ATTR(max_locking_protocol, S_IFREG | S_IRUGO,
 467                ocfs2_max_locking_protocol_show, NULL);
 468
 469 static ssize_t ocfs2_loaded_cluster_plugins_show(struct kobject *kobj,
 470                                                  struct kobj_attribute *attr,
 471                                                  char *buf)
 472 {
 473         ssize_t ret = 0, total = 0, remain = PAGE_SIZE;
 474         struct ocfs2_stack_plugin *p;
 475
 476         spin_lock(&ocfs2_stack_lock);
 477         list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
 478                 ret = snprintf(buf, remain, "%s\n",
 479                                p->sp_name);
 480                 if (ret < 0) {
 481                         total = ret;
 482                         break;
 483                 }
 484                 if (ret == remain) {
 485                         /* snprintf() didn't fit */
 486                         total = -E2BIG;
 487                         break;
 488                 }
 489                 total += ret;
 490                 remain -= ret;
 491         }
 492         spin_unlock(&ocfs2_stack_lock);
 493
 494         return total;
 495 }
 496
 497 static struct kobj_attribute ocfs2_attr_loaded_cluster_plugins =
 498         __ATTR(loaded_cluster_plugins, S_IFREG | S_IRUGO,
 499                ocfs2_loaded_cluster_plugins_show, NULL);
 500
 501 static ssize_t ocfs2_active_cluster_plugin_show(struct kobject *kobj,
 502                                                 struct kobj_attribute *attr,
 503                                                 char *buf)
 504 {
 505         ssize_t ret = 0;
 506
 507         spin_lock(&ocfs2_stack_lock);
 508         if (active_stack) {
 509                 ret = snprintf(buf, PAGE_SIZE, "%s\n",
 510                                active_stack->sp_name);
 511                 if (ret == PAGE_SIZE)
 512                         ret = -E2BIG;
 513         }
 514         spin_unlock(&ocfs2_stack_lock);
 515
 516         return ret;
 517 }
 518
 519 static struct kobj_attribute ocfs2_attr_active_cluster_plugin =
 520         __ATTR(active_cluster_plugin, S_IFREG | S_IRUGO,
 521                ocfs2_active_cluster_plugin_show, NULL);
 522
 523 static ssize_t ocfs2_cluster_stack_show(struct kobject *kobj,
 524                                         struct kobj_attribute *attr,
 525                                         char *buf)
 526 {
 527         ssize_t ret;
 528         spin_lock(&ocfs2_stack_lock);
 529         ret = snprintf(buf, PAGE_SIZE, "%s\n", cluster_stack_name);
 530         spin_unlock(&ocfs2_stack_lock);
 531
 532         return ret;
 533 }
 534
 535 static ssize_t ocfs2_cluster_stack_store(struct kobject *kobj,
 536                                          struct kobj_attribute *attr,
 537                                          const char *buf, size_t count)
 538 {
 539         size_t len = count;
 540         ssize_t ret;
 541
 542         if (len == 0)
 543                 return len;
 544
 545         if (buf[len - 1] == '\n')
 546                 len--;
 547
 548         if ((len != OCFS2_STACK_LABEL_LEN) ||
 549             (strnlen(buf, len) != len))
 550                 return -EINVAL;
 551
 552         spin_lock(&ocfs2_stack_lock);
 553         if (active_stack) {
 554                 if (!strncmp(buf, cluster_stack_name, len))
 555                         ret = count;
 556                 else
 557                         ret = -EBUSY;
 558         } else {
 559                 memcpy(cluster_stack_name, buf, len);
 560                 ret = count;
 561         }
 562         spin_unlock(&ocfs2_stack_lock);
 563
 564         return ret;
 565 }
 566
 567
 568 static struct kobj_attribute ocfs2_attr_cluster_stack =
 569         __ATTR(cluster_stack, S_IFREG | S_IRUGO | S_IWUSR,
 570                ocfs2_cluster_stack_show,
 571                ocfs2_cluster_stack_store);
 572
 573 static struct attribute *ocfs2_attrs[] = {
 574         &ocfs2_attr_max_locking_protocol.attr,
 575         &ocfs2_attr_loaded_cluster_plugins.attr,
 576         &ocfs2_attr_active_cluster_plugin.attr,
 577         &ocfs2_attr_cluster_stack.attr,
 578         NULL,
 579 };
 580
 581 static struct attribute_group ocfs2_attr_group = {
 582         .attrs = ocfs2_attrs,
 583 };
 584
 585 static struct kset *ocfs2_kset;
 586
 587 static void ocfs2_sysfs_exit(void)
 588 {
 589         kset_unregister(ocfs2_kset);
 590 }
 591
 592 static int ocfs2_sysfs_init(void)
 593 {
 594         int ret;
 595
 596         ocfs2_kset = kset_create_and_add("ocfs2", NULL, fs_kobj);
 597         if (!ocfs2_kset)
 598                 return -ENOMEM;
 599
 600         ret = sysfs_create_group(&ocfs2_kset->kobj, &ocfs2_attr_group);
 601         if (ret)
 602                 goto error;
 603
 604         return 0;
 605
 606 error:
 607         kset_unregister(ocfs2_kset);
 608         return ret;
 609 }
 610
 611 /*
 612  * Sysctl bits
 613  *
 614  * The sysctl lives at /proc/sys/fs/ocfs2/nm/hb_ctl_path.  The 'nm' doesn't
 615  * make as much sense in a multiple cluster stack world, but it's safer
 616  * and easier to preserve the name.
 617  */
 618
 619 #define FS_OCFS2_NM             1
 620
 621 static ctl_table ocfs2_nm_table[] = {
 622         {
 623                 .ctl_name       = 1,
 624                 .procname       = "hb_ctl_path",
 625                 .data           = ocfs2_hb_ctl_path,
 626                 .maxlen         = OCFS2_MAX_HB_CTL_PATH,
 627                 .mode           = 0644,
 628                 .proc_handler   = &proc_dostring,
 629                 .strategy       = &sysctl_string,
 630         },
 631         { .ctl_name = 0 }
 632 };
 633
 634 static ctl_table ocfs2_mod_table[] = {
 635         {
 636                 .ctl_name       = FS_OCFS2_NM,
 637                 .procname       = "nm",
 638                 .data           = NULL,
 639                 .maxlen         = 0,
 640                 .mode           = 0555,
 641                 .child          = ocfs2_nm_table
 642         },
 643         { .ctl_name = 0}
 644 };
 645
 646 static ctl_table ocfs2_kern_table[] = {
 647         {
 648                 .ctl_name       = FS_OCFS2,
 649                 .procname       = "ocfs2",
 650                 .data           = NULL,
 651                 .maxlen         = 0,
 652                 .mode           = 0555,
 653                 .child          = ocfs2_mod_table
 654         },
 655         { .ctl_name = 0}
 656 };
 657
 658 static ctl_table ocfs2_root_table[] = {
 659         {
 660                 .ctl_name       = CTL_FS,
 661                 .procname       = "fs",
 662                 .data           = NULL,
 663                 .maxlen         = 0,
 664                 .mode           = 0555,
 665                 .child          = ocfs2_kern_table
 666         },
 667         { .ctl_name = 0 }
 668 };
 669
 670 static struct ctl_table_header *ocfs2_table_header = NULL;
 671
 672
 673 /*
 674  * Initialization
 675  */
 676
 677 static int __init ocfs2_stack_glue_init(void)
 678 {
 679         strcpy(cluster_stack_name, OCFS2_STACK_PLUGIN_O2CB);
 680
 681         ocfs2_table_header = register_sysctl_table(ocfs2_root_table);
 682         if (!ocfs2_table_header) {
 683                 printk(KERN_ERR
 684                        "ocfs2 stack glue: unable to register sysctl\n");
 685                 return -ENOMEM; /* or something. */
 686         }
 687
 688         return ocfs2_sysfs_init();
 689 }
 690
 691 static void __exit ocfs2_stack_glue_exit(void)
 692 {
 693         lproto = NULL;
 694         ocfs2_sysfs_exit();
 695         if (ocfs2_table_header)
 696                 unregister_sysctl_table(ocfs2_table_header);
 697 }
 698
 699 MODULE_AUTHOR("Oracle");
 700 MODULE_DESCRIPTION("ocfs2 cluter stack glue layer");
 701 MODULE_LICENSE("GPL");
 702 module_init(ocfs2_stack_glue_init);
 703 module_exit(ocfs2_stack_glue_exit);